Packet data networks provide a facility for communicating data in the form of internet packets to and from communicating devices or nodes. The packet data network may provide a facility for mobile communications with a node (referred to generally as a mobile node) using, for example a radio access interface, which allows the communicating device node to be mobile within a radio coverage area provided by the network. For example, the General Packet Radio Service (GPRS) is a telecommunications standard developed by the 3rd Generation Project Partnership (3GPP) which provides a facility for communicating internet packets via a radio access interface. A GPRS network can be formed using a Global System for Mobiles (GSM) or a Universal Mobile Telecommunications System (UMTS) backbone network. GPRS provides support for packet-orientated services and attempts to optimise network and radio resources for packet data communications using the Internet Protocol (IP).
The Internet Engineering Task Force (IETF) is a body, which is responsible for developing internet protocols for facilitating communications via the internet. For example, a well established internet protocol is the internet protocol version 4 (IPV4) which has been developed and standardised for personal computers to access the internet. The IETF has also developed a further standard known as the internet protocol version 6 (IPV6) which provides an improvement with respect to the IPV4 in terms of facilitating mobile communications and increased addressing options for user equipment. Both IPv4 and IPv6 provide a facility in which a mobile node can roam from the mobile node's home network to a visited network and support an internet protocol communications session.